So far, an air compressor is widely being used in a construction site to supply compressed air to a driving tool, such as a nail driving machine, using compressed air. The air compressor generates compressed air in a compressed air generating unit by driving a motor unit, and stores the generated compressed air in a tank unit. The stored compressed air of high pressure is reduced to predetermined pressure by a pressure reducing valve and then is supplied to the driving tool (for example, see Patent Document 1).
In the operation in the construction site or the like, the air compressor is often installed outdoors. For example, under scorching sun of midsummer, an air compressor may be installed and used on the concrete or may be installed and used inside the vehicle, and the temperature of the air compressor greatly rises depending on the environmental temperature (ambient temperature). Further, when the air compressor is installed inside the vehicle, and when the air compressor is installed on a wall side such as a building, the flow of the cooling air (air cooling) caused by an axial flow fan (a blower) or the like of the air compressor was blocked, and there was a risk of causing an excessive temperature rise.
Patent Document 1: Japanese Patent Publication No. 2009-55719
When the air compressor rises in temperature, the impedance of the motor unit is increased or a grease of a bearing unit flows out to cause a poor lubrication, the bearing is worn away, a gap of a sliding unit in the compressor (compressed air generating unit) decreases and sealing sections come into close contact with each other. Thus, there was a problem of an increase in load of the compressor. Furthermore, the abrasion proceeds by the close-contact of the sealing sections, and there was a risk of a damage of the sealing member (lip ring).
Further, an error may occur in the electronic component due to the temperature rise of the air compressor, or the sealing sections may break down by heat destruction or the like. In order to perform the error correction by restart, when an error occurs in some cases, there was also a need to temporarily suspend the operations. In some cases, there was a risk that the noise suppression components or the coil or the like cause a malfunction due to high temperature demagnetization and magnetic saturation, due to the temperature rise of the air compressor. In some cases, a trouble occurs in the operation of a user by these phenomena to cause a decrease in work efficiency.
To prevent the excessive temperature rise of the air compressor, a method of reducing the output of the motor unit or the like during a high temperature to reduce the load is also conceivable. However, since the rotational speed of the axial flow fan for cooling the motor unit and the like is also lowered with a decrease of output, there was a risk of a deterioration of the heat dissipation property. Further, although the method of performing the output reduction may be effective in some portions, there is also a risk of an occurrence of failure or the like in other portions, and the overall effects are not sufficient.